JEE Main Session 1 Mole Concept 2025 Important Question for Exam Day

JEE Main Session 1 Mole Concept 2025 Important Question for Exam Day (Image Credits: pexels.com).

JEE Main Session 1 Mole Concept 2025 Important Question for Exam Day: As only 10 days are left for the JEE Main Session 1 Examination 2025 to commence, candidates appearing for the examination can check the important questions from the previous year's question paper for mole concept in the JEE Main Chemistry question paper. As per the JEE Main Chemistry 2025 weightage, mole concept questions will be asked for 4 marks. Candidates can check the JEE Main Session 1 Mole Concept 2025 Important Question for Exam Day available here.

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JEE Main Session 1 Mole Concept 2025 Important Question for Exam Day

The important JEE Main Session 1 Mole Concept 2025 questions are listed below.

The number of atoms in the following samples of substances is the largest in:
a) 127.0g of iodine
b) 48.0g of magnesium
c) 71.0g of chlorine
d) 4.0g of hydrogen
Answer: d
The ratio of mass per cent of C and H of an organic compound (CxHyOz) is 6:1. If one molecule of the above compound ( CxHyOZ ) contains half as much oxygen as required to burn one molecule of compound CXHY completely to CO2 and H2O. The empirical formula of compound CxHyOz is :
a) C2H4O
b) C3H4O2
c) C2H4O3
d) C3H6O3
Answer: c
The concentrated sulphuric acid that is peddled commercially is 95% H2SO4 by weight. If the density of this commercial acid is 1.834 g cm-3, the molarity of this solution is
a) 17.8 M
b) 15.7 M
c) 10.5 M
d) 12.0 M
Answer: a
The ratio of masses of oxygen and nitrogen in a particular gaseous mixture is 1:4. The ratio of a number of their molecule is:
a) 1:8
b) 3:16
c) 1:4
d) 7:32
Answer: d
3g of activated charcoal was added to 50 mL of acetic acid solution (0.06N) in a flask. After an hour it was filtered and the strength of the filtrate was found to be 0.042 N. The amount of acetic acid adsorbed (per gram of charcoal) is:

a) 42 mg
b) 54 mg
c) 18 mg
d) 36 mg
Answer: c
The density of a solution prepared by dissolving 120 g of urea (mol. mass = 60 u) in 1000 g of water is 1.15 g/mL. The molarity of this solution is
a) 2.05 M
b) 0.50 M
c) 1.78 M
d) 1.02 M
Answer: a
The ratio of number of oxygen atoms (O) in 16.0g oxygen (O), 28.0 g carbon monoxide (CO) and 32.0g oxygen (O₂) is :
(Atomic mass :C =12, O =16 and Avogadro’s constant N_A = 6.0 * 10²³ mol^-1)
a) 3:1:1
b) 1:1:2
c) 3:1:2
d) 1:1:1
Answer: d
When CO₂ (g) is passed over red hot coke it partially gets reduced to CO(g). Upon passing 0.5 litre of CO₂ (g) over red hot coke, the total volume of the gases increased to 700 mL. The composition of the gaseous mixture at STP is :
a) CO₂ = 200 mL: CO = 500ml
b) CO₂ = 350 mL: CO = 350ml
c) CO₂ = 0.0 mL: CO = 700ml
d) CO₂ = 300 mL: CO = 400ml
Answer: d
An open vessel at 300 K is heated till ⅖ th of the air in it is expelled. Assuming that the volume of the vessel remains constant, the temperature to which the vessel is heated is :
a) 750 K
b) 400 K
c) 500 K
d) 1500K
Answer: c
The density of 3M solution of sodium chloride is 1.252 g mL-1. The molality of the solution will be (molar mass, NaCl = 58.5 g mol-1)
a) 2.18 m
b) 3.00 m
c) 2.60 m
d) 2.79 m
Answer: d

As per the JEE Main Session 1 Syllabus 2025, the Mole Concept chapter contains sub-topics such as atomic and molecular mass, molar mass, gram atomic mass and gram molecular mass. Candidates are advised to thoroughly go through the syllabus to not miss any of the concepts.

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JEE Main Expected Attempt vs Percentile Marks |

Correct Attempts	Expected Percentile
10 Correct Attempts	10 Correct Attempts in JEE Main Jan 2025 vs Expected Percentile Marks
15 Correct Attempts	15 Correct Attempts in JEE Main Jan 2025 vs Expected Percentile Marks
20 Correct Attempts	20 Correct Attempts vs Expected Percentile Marks in JEE Main 2025 Session 1
47 Correct Attempts	JEE Main 47 Correct Attempt Vs Expected Percentile Marks 2025 Session 1